BAE Systems’ Helmet Mounted Symbology System (HMSS)

BAE Systems is rolling out its helmet mounted symbology system (HMSS) to pilots of the Eurofighter Typhoon. It displays critical information in front of the pilot’s eyes, enabling them to ‘see through’ the body of the aircraft and designate targets just by looking at them, even behind or beneath the aircraft.

Strategic Defence Intelligence talked to Richard Taylor, programme manager for HMSS.

The requirement for a symbology display helmet with ‘look at shoot’ capability has been a prerequisite for the Typhoon since the beginning of the programme. After years of development and flight trials, the HMSS is now being rolled out to UK Royal Air Force (RAF) pilots, with other Eurofighter partner nations to follow.

The helmet was originally based on a similar product developed for helicopter pilots, but has been extensively modified for the Typhoon environment. A pilot wearing the helmet sees a reflected image on the visor, displaying a symbology of objects picked up by the aircraft’s sensors.

“Symbology is a standard representation of real-world objects,” explains Taylor. “It displays what you might see in a regular heads up display; triangles to represent enemy aircraft, for example. If you’re landing, you’ll know by the cueing in the helmet what aircraft are around in your area, reducing pilot workload. “

Voice control

It also interacts with a voice control system, enabling the pilot to designate an enemy aircraft or missile as a target by looking at it, and then fire at it by speaking a command.

“If the target is outside the field of vision, such as below the aircraft or to one side of it, it will also cue the pilot to look over that way,” says Taylor. “Once they track it, the system will keep tracking it, so they can engage targets over their shoulder by looking at them, designating them and then pointing the aircraft towards it. It makes targeting a lot simpler for the pilot — Top Gun would have been a very dull film if Tom Cruise’s character had had an HMSS!”

The pilot’s head movements are captured by fixed sensors fitted around the cockpit, which detect LEDs on the back of the helmet that act as optical trackers. The avionics system interprets where the pilot’s head is by the LEDs it can see, triangulating the head position so it knows where the pilot is looking.

Avionics capability

Taylor says that the biggest challenge was integrating an avionics capability into a crash helmet. “The helmet not only has to have the symbology display technology in it, it also has to protect the pilot in the event of an ejection,” he says. “It also has to be light so that when the pilot is pulling G [experiencing G-force] it doesn’t damage their neck, and the weight has to be balanced so that it doesn’t skew to one side and the pilot feels comfortable wearing it for a long time.

“It also proved challenging to get all of the display technology to work in such a compact space with a curved surface, while ensuring the pilot is comfortable and does not experience eye strain. This, combined with the fact that the electronics have to be ruggedised and qualified to Eurofighter specifications, means that few components used in the HMSS are off-the-shelf.

“The components have to withstand vibrations and ejecting at high speed, as well as impact, dust and sand,” says Taylor. “The helmet is qualified to the normal standards for the cockpit, but also must take into account the fact that it is sat on someone’s head and has to provide protection as well.”

As the system is designed to be worn for long periods at a time, each pilot is individually fitted for their own helmet like a tailor-made suit for comfort and usability. BAE Systems are also delivering training for HMSS aircrew and maintenance personnel.

International roll-out

The next stage for HMSS will be to roll it out to the air forces of other Eurofighter partner countries.

“Getting the HMSS into service was a combination of the efforts of a lot of people and I am very keen to introduce this to other air forces now,” says Taylor. “The Germans, Italians and Spanish will start using it soon, and getting it rolled out and receiving helpful feedback from the pilots can only be a good thing.”

The feedback will influence any future developments and enhancements for the HMSS.

“The feedback we have had to date has been based around the fact that the basic capability is excellent,” says Taylor. “Any changes are likely to centre on the display. It’s about making best use of the display capability we have, much like buying a DVD player and deciding what film to watch.”

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